The present invention relates to particles of polyolefins the surface region of which is halogenated, especially such polyolefin particles containing a blowing agent, and a process for preparing the same. The polyolefin particles having a halogenated surface region of the present invention are novel materials which have not been known from any literatures.
Hitherto, expanded resin articles rich in elasticity have been prepared by using polyethylene, polypropyrene or a mixture of polystyrene and polyethylene as a raw material. However, expandable beads of these resins containing volatile liquid or gaseous blowing agents are very poor in retention of the blowing agents. Therefore, these resins cannot be sold in the form of expandable beads unlike expandable polystyrene beads, and have been sold as pre-expanded particles expanded once in a predetermined expansion ratio or as expanded articles.
It is an object of the present invention to provide polyolefin particles which can be impregnated with volatile blowing agents and which can retain the impregnated blowing agents for a long term.
A further object of the present invention is to provide expandable polyolefin particles superior in retention of volatile blowing agents.
These and other objects of the present invention will become apparent from the description hereinafter.